1. Field of the Invention
The present invention relates to the art of for cleaning contact lenses and in a specific embodiment to apparatus for performing a multi-step cleansing of contact lenses where, during a first step, cleansing is performed using a high and substantially constant concentration of the cleansing agent or agents in the cleansing fluid and where, during a second, subsequent step, the cleansing agent or agents are neutralized and/or the cleansing fluid is altered in order to make the cleansed contact lenses more suitable for insertion onto a users eyes.
2. Description of the Related Art
A high concentration of the cleaning substance in the cleaning fluid is required, because some of the impurities usually deposited on the lenses require a long exposure time to a disinfection fluid, e.g. hydrogen peroxide with a concentration of 3-4 vol. %, in order to be removed. Examples of such impurities are acanthameoba, candida albicans, yeast cells, different vira and different bacteria spores. These impurities are known to be very resistant to commonly used disinfection fluids, so in order to remove such impurities, a long exposure time is required with a high concentration of the active substance in the disinfection or cleansing fluid.
Furthermore, e.g. bacteria can excrete chemical/biological substances which can encapsulate the bacteria, i.e. form a film of chemical/biological substances which adhere to the surface of a contact lens. Thus, a long exposure time is also required in order for the disinfection or cleansing fluid to penetrate and thereby remove the bacteria and bacteria spores and the film of chemical/biological substances.
In fact, most of the presently known apparatus and methods may be denoted as bacteriostatic in that the interaction with the cleansing fluid is only sufficient for maintaining a level of bacterial contamination in the container used for holding the contact leans during cleansing.
Known apparatus for cleansing contact lenses are typically ones in which the contact lens and the cleansing fluid are introduced into a container. However, in order to avoid requiring that the user himself has to introduce an agent for neutralizing the cleansing fluid (in order to render the contact lens suitable for introduction onto the users eye), this neutralizing agent is introduced from the beginning of the process. Consequently, the neutralization of the cleansing fluid takes place during the full process, whereby the concentration of the cleansing agent is only optimum for a short period of time. Naturally, this requires a longer period of time for a suitable cleansing of the contact lens.
Apparatus which attempt to postpone the active neutralization process of the disinfection fluid are known from EP 2 658 422. In this apparatus the neutralizing agent is placed in the container wherein the disinfection process takes place by means of a mechanical device. This mechanical device can be driven by an electric motor or it can be driven manually.
Another apparatus which attempts to postpone the relief of a neutralising agent is known from GB 2 301 1 98 A. In this apparatus the neutralising agent is kept in a cavity defined by a tubular part being open ended in one end only. The cavity is sealed by a lid settled inside the tubular part, which lid swells when in contact with a disinfecting fluid. As the lid is settled inside the tubular part, a cavity, defined by side parts of the tubular part and the lid, is present on top of the lid. Due to the small dimension of the apparatus and the surface tension in the disinfecting fluid, air bubbles will tend deposit in this cavity in use. If an air bubble deposits in the cavity, access to the surface of the lid is hindered and the swelling process will not take place, whereby no access for the cleaning fluid to the neutralising agent is provided and the neutralisation process does not take place. Furthermore, the introduction of the apparatus into a receptacle used for the cleaning process is critical in the sense that no swelling of the lid will occur, if the apparatus xe2x80x9clandsxe2x80x9d standing on its open end, due to the fact that no fluid or not a sufficient amount of the fluid will be able to get into contact with the lid.
Other manners of delaying the introduction of the neutralizing agent would be using the well known sustained release principle where the agent is formed into a pill or pellet covered by a layer dissolved by the cleansing agent. In this manner, the neutralizing agent is not released until the layer has been dissolved. This method, however, has the disadvantage that the material of the layer and e.g. pill manufacturing helping agents will be released to the cleansing agent, part of which will be introduced onto the eye of the user or will remain in the container means used for the cleansing. These materials are typically of a type that attracts and holds bacteria and, consequently, facilitates bacterial growth in the container means and hence on the contact lenses.
Thus, it is an object of the invention to provide a container means for use in cleansing a contact lens, which firstly is able to reduce or fully obviate the introduction of unsuitable agents (mostly agents irritating to the eye) in the cleansing fluid, and which secondly is adapted to fully delay the neutralization of the cleansing agent until after a desired period of time where the contact lens has been sufficiently cleansed. Both these objects will help to reduce the bacterial growth in the container used for the cleansing and thereby the concentration of bacterial present on the cleansed contact lens. Thus, the present method will facilitate bactericide cleansingxe2x80x94that is, a cleansing actually reducing the number of bacteria in the container and, thus, on the cleansed contact lens.
These objects are obtained by a container means suitable for holding at least one substance for use in a process for cleaning contact lenses using a fluid, the container means comprising:
at least one first and at least one second part assembled/combined to form a sealed cavity for holding the at least one substance,
the second part(s) being formed of a material having a second expansion coefficient when embedded in the fluid and being at least substantially insoluble in the fluid, the second part(s) having outer surface(s) constituting part(s) of an outer surface of the container means,
the first part(s) being formed of a material having a first expansion coefficient when embedded in the fluid and being at least substantially insoluble in the fluid, the first expansion coefficient being smaller than the second expansion coefficient,
wherein
the container means has at least one cross section wherein the first part(s) define(s) an envelope curve and wherein at least one part of the second part(s) extend(s) outside the envelope surface,
and/or
two or more parts of the outer surface of the assembled/combined container means are constituted by surface parts of the second part(s) at at least two different sides thereof.
It should be noted that, in the present context, an expansion coefficient may be negative so that the material, in fact, shrinks when in contact with the fluid.
In the following, the invention will be described where one of the materials expands more than the other. It should be noted that exactly the same effect will be achieved if the other material shrinks correspondingly in relation to the first material.
The material being able to expand should be at least substantially insoluble in the so as to avoid polution of the fluid used in the process for cleaning contact lenses. Polution may e.g. be the case where the material is no longer interconnected so that the material is able to deposit on the lenses. It is preferred that the fraction of the material no longer being interconnected should be less than 5%, preferably less than 4%, such as less than 3%, preferably less than 2%, such as less than 1%, preferably less than 0.5, even less than 0.25% and preferably less than 0.125%, the amount being measured in mass fraction.
In the following context, the envelope curve is a curve where all concavities are replaced by straight lines so that only convexities and straight lines remain.
One advantage obtained by part of the second part extending outside the envelope curve of the first parts is that should the container means xe2x80x9clandxe2x80x9d on a surface in the area where the cavities of the first part(s) are, the part(s) of the second parts will extend beyond these parts, whereby the fluid will gain access to these part(s) of the second parts. If the first part(s) and a bubble or a receptacle holding the container means, the fluid etc. were to be able to fully enclose the outer surface of the first part(s), no release of the substance would take place. Thus, this feature of the invention will act to enhance the chance of the release of the substance taking place.
Also, when the part(s) of the second part(s) extends outside the envelope, it will be less probable for a bubble to cover all of the extending part(s), whereby also this effect is made much more improbable.
In this context, the fact that parts of different sides of the outer surface of the container means are constituted by parts of the second part(s) means that should the container means xe2x80x9clandxe2x80x9d on one of those sides, the other side will not be blocked by the contact between the container means and a receptacle holding the container means, the fluid etc.
More specifically, two different sides would typically be different parts of the container means as seen from two directions at an angle of at least 20 degrees, preferably at least 30 degrees, such as at least 45 degrees, preferably at least 60 degrees, such as at least 90 degrees, preferably on the order of 180 degrees.
An advantage obtained by this feature is the fact that, should one side be blocked either by a bubble or by the container means xe2x80x9clandingxe2x80x9d on that side, the other side would typically be exposed to the fluid, whereby the release of the substance will not be hampered.
The fluid used may simply be water and the substance a disinfecting or cleansing agent, such as an enzyme, or the fluid may itself be a disinfecting or cleansing fluid and the substance a neutralising agent. Common to the process or holding means is the fact that the access to the substance is delayed in order to divide the cleansing process into two distinctly different phasesxe2x80x94one with and one without the interaction of the substance.
In a preferred embodiment, the first part defines an open cavity and the second part defines a cover at least substantially closing the cavity of the first part.
In this embodiment, the second part may abut the first part along an inner or an outer surface part thereof, at least part of the inner or outer surface part of the first part being at an angle to the predetermined direction. In this manner, the difference of expansion will generate access to the substance, as two parts of the first and second parts, respectively, abutting in the unexpanded state of the holding means, will not expand to the same degree, whereby the abutment will be removed and, consequently, an opening be generated.
Alternatively or additionally, the second part may abut the first part along an end surface part thereof, the end surface part typically corresponding to e.g. the upper edge of a cup or similar container.
In this situation, the difference in expansion will not automatically generate access to the substance, as the expansion of two abutting parts (as above) will be in substantially the same direction. Therefore, the difference in expansion should be large enough for the abutting surface parts of the first and second parts to disengage and thereby form access to the substance in the holding means. In other words, the dimensioning of the first and second parts and the first and second expansion coefficients are preferably chosen so that, subsequent to the expansion of the first and/or second parts, an opening is defined between the first and second parts and at the at least part of the end surface part. Thus, if the abutting surface parts form eg a circle, the difference in expansion is preferably larger than the largest thickness of the abutting surface parts in order to ensure that a gap is formed.
In the preferred embodiment, the second part preferably has a tubular part, an outer edge portion of which is to be exposed to the fluid. This tubular part has an advantage when the expansion of the first and/or second parts is e.g. a swelling. The swelling of a tubular part is an overall increase in the diameter or dimensions of the tubular part. When the outer edge portion is to be exposed to the fluid, the expansion will be quickest at this edge portion so that the expansion of the tubular part will be a funnel-shaped deformation due to the expansion along the full circumference pressing the expanded material outwards.
In another embodiment, the first part defines a plurality of open cavities, the second part defining a cover at least substantially closing the cavities of the first part.
As will be clear from the following, this funnel-shaped deformation may also be used for timing the release of several substances in the fluid.
It may be preferred that the first part defines a plurality of open cavities, the second part defining a cover at least substantially closing the cavities of the first part. In this situation, it may be desired that access to substances present in the individual cavities is timed differently.
One manner of obtaining this timing is one wherein the plurality of open cavities are positioned at least substantially concentrically and are separated by separating walls of the first part. Naturally, these cavities need not be circular.
In this situation, the tubular part preferably encircles an outer cavity of the open cavities in order to take advantage of the above-mentioned funnel-shaped deformation.
Preferably, the first and second parts are biased towards each other. As those first parts of the second part which firstly deform and expand will typically be the outer parts thereof, these will not be suitable for providing this biasing: they would quickly release the closure and thereby provide access to the contents of all cavities in the first element. Therefore, this biassing may be obtained by biassing the separating walls of the first part toward internal biassing means of the second part, the separating walls and/or the biassing means closing, at least in an unexpanded state, one of the cavities of the first part. This closure may be obtained by the closing action of the first part being kept in place by the biassing. In this manner, the access to contents of this one cavity will be prevented at the point in time where access is obtained to the outer cavity.
In that situation, the thickness of the biassing means and/or especially the part of the second part defining the closure of the at least one of the cavities may be adapted so that the opening of this cavity takes place a predetermined time after contacting the holding means and the fluid or after the point in time where the fluid gained access the outer cavities.
Another manner of providing a plurality of cavities is aligning these side by side in the first part, the open cavities being separated by separating walls. In this situation, the tubular part is preferably positioned so as to have an axis of symmetry along the aligned open cavities.
The funnel-shaped deformation of the tubular part naturally depends on the manner in which the expansion takes place along the circumference of the tubular part. Preferably, the outer edge portion is positioned at least substantially within a plane, such as within a few times the thickness of the material of the first or second parts at that position, in order to ensure that the expansion of the material in fact provides the funnel-shaped deformation.
As described above, the funnel-shaped deformation is generated by the outer parts of the tubular part expanding more quickly than the more central parts thereof. As this deformation has the above advantages, it is preferred that, at the outer edge portion, the second part has, compared to a main part of the second part, a larger proportion of the part of the surface thereof to be exposed to the fluid in relation to the volume of the material. This may be provided by increasing the surface to be exposed to the fluid but also by reducing e.g. the thickness of the material of the second element compared to the thickness at other parts of the second part.
Thus, by selecting the thickness of the material of the second part, timing of the release of the individual substances may be selected, such as in a way that e.g. only a short time is needed for getting access to a first closed cavity due and e.g. a relatively longer time period is needed to gain access to a second closed cavity. In such a case, thickness of the second part that is closing the first cavity would be substantially thinner than the part closing the second cavity.
As described above, it is preferred that the first and the second part are biased toward each other.
For example, the first and the second parts may be shaped so as to be combined without the use of any separate fixing or combining means.
Alternatively, two parts actually defining the cavity may be provided and assembled using a separate fixing means, such as a fixing means holding the two parts in place, the fixing means having a coefficient of expansion larger than the two elements so that the fixing means will, at a point in time, release the two parts so that these may separate and release the substance held thereby.
The lack of glue or other additional substances has e.g. the advantage that no additional substances, such as glue etc, are required in order to hold the two parts in place during the first part of the cleansing process. These additional substances might not be desired in the cleansing fluid, as part of this might adhere to the contact lens when introduced onto the eye of the user.
The above embodiment has been described as one where the first part defines a cavity and the second part closes the cavity. Naturally the same advantages and effect may obtained when the second part defines a cavity and the first closes the cavity.
The first expansion coefficient may be one where a sheet of the material of the first part having a thickness of 1 mm in an unexpanded condition will expand to a mean thickness of 0.5-10 mm, such as a thickness of 0.7-1.5 mm, preferably a thickness of 1 mm, when fully expanded in the fluid.
The second expansion coefficient may be one where a sheet of the material of the second part having a thickness of 1 mm in an unexpanded condition will expand to a mean thickness of 1-10 mm, such as a thickness of 1.2-5 mm, preferably a thickness of 1.4-2 mm, when fully expanded in the fluid.
However, such materials can have an even larger expansion once the substance has been released into the fluid. The presently preferred material has an expansion of the order of 200% in the H2O2 but on the order of more than 500% in pure water which would results from an neutralisation of the H2O2 with catalase.
Preferably, the second expansion coefficient is larger than the first expansion coefficient, and the materials of the first and second parts are preferably so that an initial, unexpanded sheet of the material of the second part and of a predetermined thickness will expand to a sheet of a mean thickness of at least 105%, such as at least 110%, such as about at least 140% of the mean thickness of a fully expanded sheet of the material of the first material and of the same initial unexpanded predetermined thickness.
Especially in embodiments where the part having the largest expansion is positioned more or less within the other part, it may be preferred that the first part is provided with means for facilitating deformation or breaking thereof at one or more predetermined points or along one or more predetermined lines in order for the expansion of the expanding part to be able to provide the access to the substance by simply breaking or deforming the other part.
Also, in this context, it should be noted that the xe2x80x9cexpansionxe2x80x9d of one of the elements in relation to the other may as well be a shrinking of the other element in relation to the first element. In order to provide the access of the fluid to the substance, only a difference in change of dimension is required.
As described above, a major problem of the prior art is the action of bubbles blocking the access of the fluid to the expanding material or that the relatively non-expanding material is able together with the receptacle is able to block this access.
This adverse effect may be removed where the at least one part of the second part(s) extending outside the envelope surface has a part being convex. In this manner, if the extending part actually forms a convex part of the outer surface of the container means, this convexity may prevent the container means from actually xe2x80x9clandingxe2x80x9d on this side. Also, bubbles are less probable to form on such convex surfaces.
In order to further improve the probability of the container means actually being oriented in the fluid in the optimum manner, the container means may further comprise orientation means for orientation of the container means relative to the horizontal direction when positioned in a receptacle, the receptacle being adapted to hold the container means, the contact lenses, and the fluid when the contact lenses are cleaned.
In this manner, the orientation means may be adapted to hold the container means with its axis of symmetry being substantially horizontal.
Also, having introduced this xe2x80x9cadditionalxe2x80x9d element, it may be used also for other purposes. Thus, it may further comprise enclosing means for enclosing the container means. As described above, the expanding material may have a total degree of expansion to a degree where it is quite large and may interact, when the user retrieves the contact lenses. Also, if the shape of the expanded material should look like a contact lens, it would be desirable to xe2x80x9cseparatexe2x80x9d it from the lenses in order to prevent the user from introducing the wrong element onto his/her eye.
Therefore, the enclosing means may comprise a porous or liquid penetrable means being adapted to allow the fluid to travel into the enclosing means and to prevent at least a major part of the expanded second part(s) from escaping the enclosing means.
In addition, the orientation means may further comprise means for holding the contact lenses during cleansing thereof.
As described above, the shape and dimensions of the container means has a large say in how and where bubbles form and how the container means can xe2x80x9clandxe2x80x9d in the receptacle.
In a presently preferred embodiment, the container means is flat in a given direction when compared with the extension thereof in the two directions perpendicular thereto and to each other.
This is especially easy to see, when combined with the directing means, as these dimensions may now firstly ensure that the xe2x80x9clidxe2x80x9d of expandable material actually gains access to the fluid, that it actually expands, that it actually provides sufficient access to the substance so that the interaction between the substance and the fluid actually takes place.
Yet another problem in this type of container means for providing a timed release of a substance in a fluid will be seen when the interaction between the fluid and the substance generates e.g. a gas. As will be clear, the expansion of the expandable material may not fully remove this from the substance or provide a large gap for the fluid to enter throughxe2x80x94and the gas to escape through. In this situation, the access of the fluid to the substance may generate an increased pressure at the substance so that the expanded material is removed furtherxe2x80x94an advantageous effect. However, it may otherwise generate a gas bubble that will not escape through the gap but actually block the gapxe2x80x94and thereby stop the process even though the material has had sufficient access to the fluid and is fully expanded.
In this specific embodiment, the container means is positioned with the given direction along a horizontal direction.
Preferably, the extension of the container means along the given direction is at least 2, such as 3, preferably 4, such as about 5, such as at least 6, preferably 10, such as 20, such as about 30, preferably 50, such as 70, preferably 85 such as 100 times smaller than the extension of the container means along any of the two directions.
Also, it is advantageous that the extension of the container means in the given direction is less than 2 mm, such as less than 1.5 mm, preferably 1 mm, such as about 0.75 mm such as at least 0.5 mm and even less than 0.3 mm.
Especially where:
the first part(s) define a cavity having a bottom part and side parts and wherein the second part(s) in the assembled/combined container means close the cavity of the first part(s),
an internal height of the side parts from an internal surface part of the bottom part is less than 2 mm, such as less than 1.5 mm, preferably 1 mm, such as about 0.75 mm such as at least 0.5 and even less than 0.2 mm, and where
the second part(s) define a cavity, the cavity having a depth in the direction of the axis of symmetry, not exceeding 2 mm, such as not exceeding 1.5 mm, preferably not exceeding 1 mm, such as about not exceeding 0.5 mm, and even not exceeding 0.1 mm,
it will be seen that the expanded second part(s) will easily disengage from the first part(s) and due to the interaction of gravity be fully removed from the cavity of the first part(s) holding the substance.
Also preferred is it when the container means has an axis of symmetry directed at least substantially along the direction of the height of the side parts of the second part(s).
From the above dimensions it may be seen that the height of the side parts are not able to hold a bubble, whereby that xe2x80x9ctrapxe2x80x9d is avoided. However, it is also preferred that the first part is not able to trap a bubble. Therefore, it is preferred that the second part(s) define a cavity, the cavity having a depth in the direction of the axis of symmetry, not exceeding 2 mm, such as not exceeding 1.5 mm, preferably not exceeding 1 mm, such as about not exceeding 0.5 mm, and even not exceeding 0.1 mm. Dimensions that small will under usual conditions not hold a bubble large enough to stop the process.
An additional manner of ensuring that the process will take place is to ensure that and the substance will be able to fully remove itself therefrom when the expanded material is fully expanded. One manner of obtaining this is to have the second part(s) define a cavity, the cavity being shaped so that, when the axis of symmetry is at least substantially horizontal, no part of the inner surface of the cavity is horizontal. Thus, the substance positioned within the cavity will fall from this cavity, when the container means is oriented in the preferred manner.
Even though the xe2x80x9cexpansionxe2x80x9d due to the contact of the fluid may be caused by a number of effects, such as due to a pH value of the fluid or a concentration of one or more saltsxe2x80x94or even the temperature of the fluid, it is preferred that at least one of the first or second parts is of a material swelling when in contact with the fluid. This swelling firstly takes part at the surface parts contacted by the fluid and firstly later the fluid enters the inner parts of the material and then expands these portions. This will provide the above-mentioned funnel-shaped deformation as an intermediate state and a final, fully expanded state of the material. Furthermore, the swelling is an effect where the swelling material simply expands but does not release, generate or emit any particles or substances, it does not react with the fluid in a manner so that additional substances are formed, whereby the above-mentioned advantages also relating to the lack of glue etc. in the combining or assembling of the container means are obtained.
In fact, a material, such as polyhema, normally used for contact lenses actually expands (polyhema expands about 40%) when in contact with water, and materials (not expanding in water) typically used for containers for holding or cleansing contact lenses may be used in the present container means. The advantage of this is that these materials have already been accepted for use in connection with contact lens cleansing so that no side effects can take place.
Another advantage of the invention is that a cleansing system may be provided which can facility cleaning of contact lenses using different cleansing agents which can not coexist. This is possible because the release of the cleansing agents can be timed so that e.g. after a cleansing process using one agent, another agent can be released.
Another possibility is the case where H2O2 with a pH-value of 3-3.5 is utilized as the disinfection fluid (in order to get a bactericide cleansing of the lenses), a release of an agent that can alter the pH-value of the cleansing fluid at the end of the cleaning process to a value that is comfortable to the user when introducing the contact lens onto the eye. This altering or neutralizing agent may be catalase. Also, at the same time, before or after, a salt may be released into the fluid in order to bring about a physiological salt concentration also more pleasant for the user of the contact lens.
In addition, the use of different enzymes, which are not able to coexist or which function better when not coexisting, may be facilitated by the presently provided different timing between the release of different substances in the fluid.
The actual timing of the release or different releases may depend on the wishes of the user or the demands of the cleansing process. Different holding means may be provided for eg long term (or optimal) cleansing and shorter term (and thus less optimal) cleansing. A long term cleansing may be one taking place over nightxe2x80x94such as where the substance or at least one of the substances is/are not released before after 2 hours, such as after 4 hours, such as after 6 hours. A short term cleansing may be one where the or a substance is released after no more than 2 hours, such as no more than 1 hour, such as no more than xc2xd hour.
In the situation where the last substance to be released is one actually stopping the cleansing process, this would be that described above. Other substances may, however, be released before in the process ofxe2x80x94or actually startingxe2x80x94the cleansing process.